643775438 has 4 divisors (see below), whose sum is σ = 965663160. Its totient is φ = 321887718.

The previous prime is 643775413. The next prime is 643775453. The reversal of 643775438 is 834577346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 834577346 = 2 ⋅417288673.

It is a junction number, because it is equal to n+sod(n) for n = 643775392 and 643775401.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160943858 + ... + 160943861.

It is an arithmetic number, because the mean of its divisors is an integer number (241415790).

Almost surely, 2^643775438 is an apocalyptic number.

643775438 is a deficient number, since it is larger than the sum of its proper divisors (321887722).

643775438 is a wasteful number, since it uses less digits than its factorization.

643775438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321887721.

The product of its digits is 1693440, while the sum is 47.

The square root of 643775438 is about 25372.7302039020. The cubic root of 643775438 is about 863.4651244405.

The spelling of 643775438 in words is "six hundred forty-three million, seven hundred seventy-five thousand, four hundred thirty-eight".